Resistance heating apparatus



y 1965 E. F. M BRIEN 3,182,167

RESISTANCE HEATING APPARATUS Filed Jan. 23, 1962 2 Sheets-Sheet lINVENTOR. EDWARD F. McBRlEN FIG. 3 3% Q1 ATTORNEY y 1965 E. F. M BRIEN3,182,167

RESISTANCE HEATING APPARATUS Filed Jan. 23 1962 2 Sheets-Sheet 2 FIG. 4

FIG. 5 82 INVENTOR. EDWARD F. Mc BRIEN ATTORNEY United States Patent f3,182,167 RESISTANCE HEATBIG APPARATUS Edward F. McBrien, Parrna, Ohio,assignor to The Ohio Crankshaft Company, Cleveland, Ohio, a corporationof Ohio Filed Jan. 23, 1962, Ser. No. 168,114 3 Claims. (Cl. 219-1059This invention pertains to the art of electrical heating and moreparticularly to an apparatus for resistance heating indefinite lengthsof electrically conductive materials.

The invention is particularly applicable to the heating of continuouslymoving wire and it will be discussed with particular reference thereto;however, it is to be appreciated that the invention has much broaderapplications and may be used for the heating of other items ofindefinite length such as metal strip, springs, tubing, etc.

In the manufacture of wire, it is often desirable to anneal or otherwiseheat treat the wire during the processing thereof. For instance, whenthe diameter of the wire is reduced by successive drawing operations,the wire is intermittently annealed to relieve cold working stresses inthe wire. In the past, such wire has been annealed by coiling the Wireonto a spool and soaking the spool in a holding furnace, which proceduregreatly increases the production cost and prevents continuous processingof the wire. In order to eliminate the requirement for soakingindividual coils of Wire, it has been suggested to continuously heat themoving wire as it is being processed; however, prior attempts toaccomplish this desired result have proven unsatisfactory. For instance,a fuel fired mufiie for continuously heating a moving wire had to beexcessively long or the speed of the moving wire had to be greatlyreduced to obtain the proper temperature in the moving wire. Aninduction coil for inducing a current into the wire as it was moving Waslimited by the reference depth and diameter relationships of the wire sothat inefficient heating resulted.

It has heretofore been proposed to heat the wire while it iscontinuously moving by electrically contacting the Wire at spaced pointson its path of movement, inter-connecting these contact points and thencausing a heating current to flow in the loop so formed, such currentsusually being induced to fiow by transformer action. Dilficulty has beenexperienced however, with such arrangements because of the arcing whichoccurs between the contacts and the wire as the Wire leaves thecontacts, which arcing tends to pit and otherwise mar the surface of thewire, making it unsuitable for further processing, or otherwise makingit unsaleable. These arrangements also required sliding engagementbetween the contacts and the moving wire which engagement tended to scarthe surface of the moving Wire.

The present invention provides apparatus of the type last describedwhich overcomes the disadvantages stated and others and allows theheating current to be introduced into the continuously moving wireWithout arcing at the contacts.

In accordance with the present invention there is provided an apparatusfor continuously heating a moving wire. This apparatus comprises firstand second rotatably mounted drums spaced from each other, the movingwire forming a conductive loop between these spaced drums. Thisconductive loop comprises a first portion of wire Wrapped partiallyaround the first drum, a second portion of wire extending between thedrums and wrapped around the second drum and a third portion of wirewrapped partially around the first drum. A transformer is providedcomprising a primary winding and a core with the core having an openingthrough which the second portion of Wire extends. The first drumcomprises a 3,182,167 Patented May 4, 1965 plurality of conductiveelements on the periphery thereof and extending in a directionsubstantially perpendicular to the first and second portions of wire andsubstantially parallel to the axis of rotation of the first drum. Thefirst drum also includes means for insulating these conductive elementsfrom each other. The second drum has a high electrical resistivityperipheral portion in contact with the second portion of the moving wireand the first and second portions of wire are in overlapped relationshipto each other on the periphery of the first drum.

The primary object of the present invention is the provision of anapparatus for heating a continuously moving wire which apparatus iseconomical to produce and durable in operation.

A further object of the present invention is the provision of anapparatus for heating a continuously moving wire which apparatus can beeasily adapted to a continuous Wire manufacturing installation.

Yet another object of the present invention is the provision of anapparatus for resistance heating a continuously moving wire whichapparatus comprises a means for forming a current conductive section andmeans for causing a current to flow in this current conductive sectionwithout arcing at the various contacts with the moving wire.

Another object of the present invention is the provision of an apparatusfor resistance heating a continously movin wire which apparatus hasmeans for forming a current conductive section in the moving Wire, meansfor electrically connecting the ends of the section and means forcausing a heating current to flow through the section without arcing atthe various contacts with the moving wire.

Still a further object of the present invention is the provision of anapparatus for resistance heating a continuously moving wire by passing ahigh heating current therethrough wherein said apparatus has anelectrical connection means dividing the heating current into aplurality of smaller branch currents at the various contact points, orother transfer points used to introduce the heating current into thewire, to prevent arcing as current passes through the contact points.

Another object of the present invention is the provision of an apparatusfor resistance heating a continuously moving wire which apparatus doesnot pit or mar the surface of the Wire.

These and other objects and advantages will become apparent from thefollowing description used to illustrate the preferred embodiments ofthe invention as read in connection with the accompanying drawings inwhich:

FIG. 1 is a side elevation view illustrating a preferred embodiment ofthe present invention;

FIG. 1a is a partial view illustrating a slight modification of thepreferred embodiment disclosed in FIG. 1;

FIG. 2 is an enlarged detailed view taken along line 22 of FIG. 1;

FIG. 3 is a diagrammatic view of the preferred embodiment disclosed inFIG. 1

FIG. 4 is a diagrammatic view of the embodiment disclosed in FIG. 1a;

FIG. 5 is a somewhat schematic view illustrating an alternativeembodiment of the present invention; and,

FIG. 6 is a somewhat schematic view illustrating still further thealternative embodiment disclosed in FIG. 5.

Referring now to the drawings wherein the showings are for the purposesof illustrating preferred embodiments of the invention and not for thepurposes of limiting same, FIG. 1 shows an apparatus A for heating awire W by passing a heating current through a section of the wire as itis continuously moving in a longitudinal direction. The apparatus isprovided with a guide means It which may take a variety of structuralforms; however, in this preferred embodiment, the guide means It)comprises a pulley, or drum, rotatably supported by an appropriatejournal 12 and having a slack adjusting means such as springs 14. It isto be appreciated that the same journal and slack adjusting arrangementis provided on the opposite, but hidden, side of drum It Spaceddownwardly from drum It) is a second guide means 16 which, in thepreferred embodiment, takes the form of a drum rotatably supported inappropriate journal 18. Located between drurns It) and I6 is aninduction heating device comprising an iron core 29 having a Window, orcentral opening 22 and a primary winding 24 electrically connected to aschematically represented generator 26. The wire W is wrapped around thedrums to form an electrically conductive loop or section of wire betweenthe drums.

The drum 1%, although it may take a variety of structural forms ischaracterized by being constructed of an insulating material or, atleast, of a material having a resistance substantially greater than theresistance of wire W. In accordance with the preferred embodiment of thepresent invention, the drum to 'has a construction quite similar to acommutator for a D.C. generator. (See FIGURE 2.) The outer periphery ofthe drum 16 is comprised of a plurality of axially extending,electrically conductive bars 32 electrically insulated from each otherby a plurality of intermediately positioned, electrical insulationstrips 34. The electrically conductive bars 32 provide a plurality ofseparate parallel electrical connections joining spaced ends 40, 42 ofthe conductive section of wire between the drums. Ends 40, 42 are thesections of wire W which are both in over-lapping relationship withrespect to each other and also incontact with the outer periphery of thedrum 16. The number of separate parallel connections is determined bythe number of electrically conducted bars in contact with and extendingbetweenthese over-lapped ends of the wire. By so constructing drum 16,the heating current I is divided into a plurality of branch currents Ixwhich are individually designated as current I (a:1) shown in FIGURE 2.The current paths of each branch current Ix have substantially equalizedimpedance because each branch current Ix flows through the same lengthof the wire being heated. For instance, branch current Ia flows throughthe heated wire section from a point at the first contact made by wireend 40, around the loop between the drums 1t) and 16, and back to theposition axially spaced from the starting point. By tracing the pathsfollowed by each branch current, it is found that the current paths eachhave the same length of wire W. Since the resistance or impedance ofeach parallel branch between Wire ends 40 and 42 is substantially thesame, the branchcurrents Ix will have a value determined by dividing theheating current I by the number of conductive bars 32 forming theparallel current conducting paths. The proper number of current paths isdetermined by increasing the angle a until the magnitudes of theindividual branch currents Ix are such that arcing is prevented betweenthe moving wire and the drum lid. To guide the wire W around theperiphery of the drum 16, it is within the contemplation of theinvention to provide grooves 44, 46. It is to be appreciated that thegrooves may be eliminated without departing from the intended scope ofthe present Moving wire W engages the surface of drum In to the left ofaxis x, moves along the surface of drum l6 past the axis'x and thenprogresses into electrically inductive relationship with primary winding24. The wire W then engages the drunrlfi at the left of axis x andextends along the surface to a point to the right of axis x, at whichposition the moving wire W leaves the surface of the drum. The path ofthe heating current I is represented by dashed arrows, and the parallelbranch currents Ix are shown as extending between the overlappingportions of the Wire W which are in engagement with the surface of thedrum 16. By increasing the angle a, the overlapping portion of themoving wire W is correspondingly increased to in clude a greater numberof conductive bars 32, which correspondingly increases the number ofparallel paths between the wire ends so that the branch current Ix ineach path is reduced. In this manner arcing between the wire and themechanical transfer device on the drum is elimi nated.

The angle a may be increased until it approximates 180 by increasing theentrance and exit angle of the moving wire W; however, as the angle aapproaches 180 the Wire W entering and leaving the drum surface issubstantially parallel, which may not be advantageous in practice. Forthis reason the angle a is increased to 180 by winding the moving wire Won drum 16 in a manner disclosed in FIG. 1a and diagrammaticallyrepresented in FIG. 4. It is noted that the moving wire contacts thedrum 16 at one side of verticalaxis y and leaves the surface of drum 16nearly 270 thereafter. As in FIG. 1, the moving wire W passes throughthe window 22 and over the insulated drum Jill. The wire W then againcontacts and travels around the surface of drum 16 through an angle ofapproximately 270 and exits in a line substantially parallel with theline of entrance. The overlapping portion of the wire W in contact withthe pe ripheral surface of the drum 16 is substantially 180 as isillustrated in FIGS. 10: and 4. It is within the contemplation of theinvention to provide other values for angle a by proper winding of themoving wire W around the drum 16.

A preferred embodiment of the present invention as described, includes ameans for inducing the heating current into a conductive section ofmoving wire in the form of a loop around two spaced drums. In accordancewith a further aspect of the present invention, the heating current maybe induced into a conductive section of the moving wire by brushes incontact with spaced guide means for the continuously moving wire. One ofsuch embodiments is disclosed in. FIG. 5 wherein a pair of guide means,such as drums 7t), '72, contact the longitudinally moving wire W atspaced points; and the drums are rotatably mounted so that there is nosliding movement between the wire and the drums. The rotatable drums'70, 72 are each constructed in a manner similar to drum 16 shown inFIG. 1 and are comprised 70 so that electrical contact may be made withseparate a conductive bars 74 by the separate brushes; In a similarmanner, drum 72 is provided with spaced brushes 90, 92, 94 and '96. Anelectrical source schematically represented at tilt) is connected to theindividual brushes.

so that current passes through the brushes, through the conductive barsin engagement with the brushes and then into the moving wire W. As sofar explained, the major portion of the heating current created bysource 104) would pass from brush 86 through the wire W to brush 90because of the lesser amount of'impedance in the length of wire betweenthe conductive bars opposite these brushes. The wire is represented inFIG. 5 as being a resistance element having a resistance Rt between thedrums and smaller resistances R adjacent the separate conductive bars onthe spaced drums and, of course, the resistance Rt is lesser than theresistance Rt plus one or more resistances R. To prevent the highheating current from flowing in the low resistance section of wirerepresented by Rt extending between brushes 86 and 90, a plurality ofimpedances El -R4 are placed within the circuits leading to theindividual brushes. The impedances increase from R1 to R4 in a ratioquite similar to the manner in which the resistance R increases frombrush 86 to brush 80. By providing the impedances within the circuitsleading to the individual brushes, the current is divided between thesebrushes to reduce the transfer current at any one brush.

Referring to FIG. 6, a practical apparatus is disclosed foraccomplishing the features shown in FIG. 5. The drums 70 and 72 are insliding engagement with the resistance elements 110, 112 which areconnected at their opposite ends through an electrical source such as abattery 114. The resistance of wires 110 and 112 increase substantiallyproportional to the increased resistance of the length of wire incontact with the conductive bars 74 in engagement with the resistancewires. In this manner, the impedance relationship disclosed in FIG. 5 isconveniently obtained.

The invention has been described in connection with a number ofstructural embodiments; however, it is not intended that the inventionshould be limited thereto and it is appreciated that variousmodifications may be made in these embodiments without departing fromthe spirit and scope of the invention as defined in the appended claims.

Having thus described my invention, I claim:

1. A heating apparatus for continuously heating a moving wire,comprising in combination: first and second rotatably mounted drumsspaced from each other, said moving Wire forming a conductive loopbetween said spaced drums, said conductive loop comprising a firstportion of said wire wrapped partially around said first drum, a secondportion of said wire extending between said drums and wrapped aroundsaid second drum and a third portion of said wire wrapped partiallyaround said first drum, a transformer comprising a primary winding and acore, said core having an opening, said second portion of said wireextending through said core opening, said first drum comprising aplurality of conductive elements on the periphery of said first drum andextending in a direction substantially perpendicular to said first andthird portions of said wire and substantially parallel to the axis ofrotation of said first drum, means for insulating said elements one fromthe other, said second drum having a high electrical resistivityperipheral portion in contact with said second portion of said movingwire, and said first and third portions of said wire being inoverlapping relationship with respect to each other on said first drum.

2. A heating device for continuously heating a moving wire, comprisingin combination: first and second rotatably mounted drums spaced fromeach other, said wire moving between said drums and forming a conductivesection of wire between said drums, each of said drums comprising aplurality of conductive elements on the periphery of said drums andextending in a direction substantially perpendicular to said wire andsubstantially parallel to the axis of rotation of the drum on which theyare located, a plurality of conductive elements of each drum being incontact with said wire at all times, a set of brushes engaging each ofsaid drums and contacting said elements with each set including aplurality of individual brushes spaced along the periphery of each drumfrom a position remote of the other drum to a position adjacent to theother drum, each of said brushes in each set having an impedancebalancing means with the impedance of each balancing means progressivelyincreasing from the remote brushes to adjacent brushes, conductive meansfor electrically connecting said sets of brushes, and means for causinga current flow between said brushes and through said section of wire.

3. A heating device for continuously heating a moving wire, comprisingin combination: first and second rotatably mounted drums spaced fromeach other, said wire moving between said drums and forming a conductivesection of wire between said drums, each of said drums comprising aplurality of conductive elements on the periphery of said drums andextending in a direction substantially perpendicular to said Wire andsubstantially parallel to the axis of rotation of the drum on which theyare located, a plurality of conductive elements of each drum being incontact with said wire at all times, a brush engaging each of said drumsand contacting said elements, said brush of each drum extending from aposition remote of the other drum to a position adjacent to the otherdrum, each of said brushes having an impedance per length of brushsubstantially equal to the impedance per length of wire in contact withthe same elements as said brushes, conductive means for electricallyconnecting the remote ends of each brush, and means for causing acurrent flow between said brushes and through said wire section.

References Cited by the Examiner UNITED STATES PATENTS 2,364,623 12/44Denneen et al. 219-1059 2,502,770 4/50 Watson t21910.61 X 2,675,461 4/54Leonard 219--10.61 X 3,008,026 11/61 Kennedy 219--l0.61 3,103,571 9/63Axelsson 21910.61

RICHARD M. WOOD, Primary Examiner.

3. A HEATING DEVICE FOR CONTINUOUSLY HEATING A MOVING WIRE, COMPRISINGIN COMBINATION: FIRST AND SECOND ROTATABLY MOUNTED DRUMS SPACED FROMEACH OTHER, SAID WIRE MOVING BETWEEN SAID DRUMS AND FORMING A CONDUCTIVESECTION OF WIRE BETWEEN SAID DRUMS, EACH OF SAID DRUMS COMPRISING APLURALITY OF CONDUCTIVE ELEMENTS ON THE PERIPHERY OF SAID DRUMS ANDEXTENDING IN A DIRECTION SUBSTANTIALLY PERPENDICULAR TO SAID WIRE ANDSUBSTANTIALLY PARALLEL TO THE AXIS OF ROTATION OF THE DRUM ON WHICH THEYARE LOCATED, A PLURALITY OF CONDUCTIVE ELEMENTS OF EACH DRUM BEING INCONTACT WITH SAID WIRE AT ALL TIMES, A BRUSH ENGAGING EACH OF SAID DRUMSAND CONTACTING SAID ELEMENTS, SAID BRUSH OF EACH DRUM EXTENDING FROM APOSITION REMOTE OF THE OTHER DRUM TO A POSITION ADJACENT TO THE OTHERDRUM, EACH OF SAID BRUSHES HAVING AN IMPEDANCE PER LENGTH OF BRUSHSUBSTANTIALLY EQUAL TO THE IMPEDANCE PER LENGTH OF WIRE IN CONTACT WITHTHE SAME ELEMENTS AS SAID BRUSHES, CONDUCTIVE MEANS FOR ELECTRICALLYCONNECTING THE REMOTE ENDS OF EACH BRUSH, AND MEANS FOR CAUSING ACURRENT FLOW BETWEEN SAID BRUSHES AND THROUGH SAID WIRE SECTION.